Zaz1920

iTrader: (1)

Hey guys,

So over the past year I've been replacing a blown engine with a ported block and getting it all running properly again. To support a Judge Ito "Aggressive street port" I installed 850cc primaries, a Supra TT fuel pump, and got a PowerFC+Datalogit that I got dyno tuned. While on the dyno I made good numbers with some minor misfiring on the top end. I figured it was the injector coils and plug wires because they were both very old. I went to replace these and ran into issues upon putting the car back together.

After replacing the ignition coils and wires and reassembling the car it's now idling at very rough 10-11 AFR. I initially suspected that there was a leak in the rat's nest because I had been trying to diagnose a minor turbo issue but I have since taken it apart again and checked every hose and actuator without finding a fault. I also verified that I have solid spark on all plugs.

At this point I have been suspecting that the PowerFC somehow reset itself to a stock map without my touching it. While I can't believe how that happened, when you have eliminated the impossible, whatever remains.....

I have contacted the shop I got a tune at and requested a digital backup of the map they put on my car, but haven't hear from them in almost a month. Is there another way to tell if this is indeed what happened?

Any other thoughts on what the issue might be?

Thanks

7-XR

iTrader: (7)

If you have a vacuum leak, I suspect the vacuum reading would jump around on the PFC. Correct me if Im wrong. I thought I lost my tune as well.... possibly when I disconnected my battery. From what Ive read you actually need to re-initialize it or reset it manually. Again please correct me if Im wrong

I am in the middle of trying to fix my rough idle.

I replaced my rats nest/ check valves a while ago and while doing so I did a few other things:
-deleted air pump (added idler pulley)
-deleted a/c
-new DP and o2 sensor
-replaced cat with mid pipe
-capped split air
-disconnected throttle body coolant lines (rusting)
-changed plugs and wires
-removed auto trans and accessories replaced with manual trans with accessories.
-relocated battery to cabin.

Im not surprised its running like crap. I kind of expected it. So I pulled off the UIM to see whats up. I found that when I bolted my UIM in the last time I over torqued it I guess and managed to crack it on the front side corner. When I removed the UIM the piece (thankfully only one chunk) just fell right off. I suspect that was source of my shitty idle which btw sounded like it was backfiring internally.

I doubt you had that problem with your UIM but you may want to check just in case.

GL!

Banzai-Racing

iTrader: (11)

Go to the injector screen and see what injector sizes are there and what the offset and scales are set at. If the primaries are 550 and not 850 then the PFC has been initialized.

How much vacuum is reading on the commander at idle?

IRPerformance

iTrader: (41)

You will never get a great idle with a pfc and the side feed 850s in the primary location. A professional tuner can get it decent, but the car will idle significantly better with the stock primaries or a more modern injector like an ID725.

Zaz1920

iTrader: (1)

Thanks for all the help so far guys.

So today I went and ran the car and took a few readings. I found that in the "injector" screen it says there are 850's all around, so the PFC didn't get re-initialized. Phew.

After starting it up it began idling really smooth with a lot of smoke (10-11 AFR) and then the smoke cleared out, but then it started getting progressively rougher back to the rough idle I have been experiencing. I actually got a log of the whole process from FC Edit that I was going to upload but it seemed to have not saved properly oh well

So I have both a boost gauge on the UIM nipple right before the LIM as well as the readings I got from the Commander, which I will show below. The Commander seemed to be reading slightly higher vacuum than the boost gauge was (Where is the boost gauge the ECU is reading from?). When the idle went rough in the end, it was surging from ~700 to ~1000 rpm. This is why I gave a range of values for all the readings I took. Here's what I recorded:

Smooth Idle:
UIM Boost Gauge - 14-15 inHg
Commander - 400mmHg

Rough Idle:
UIM Boost Gauge - 10 +/- 2 inHg
Commander - <200-300 mmHg
AFR - 10-11+

So I'm thinking that there is a boost leak somewhere that got fixed marginally but the seal fell apart as the car continued running. And it would make sense this leak is nearer the UIM Boost Gauge than the stock boost gauge. Does this sound correct? Perhaps I should check the seal between the UIM and LIM as 7-Xr had mentioned. I always tighten to the FSM's specs so I don't know why there would be an issue there.

Also, to touch on IRPerformance's comment - the car was running smooth and great when I first got it back from the shop. This rough idle - a surging between 700-1000 rpm - is extreme and undriveable. Something happened between it getting tuned properly and it now not being able to run properly and that's what I'm trying to figure out.

OG BBF

But is the idle hunting? Or just high? Instead of covering everything it could be. Take things one step at a time.

check for vaccume leaks....

check values of tps sensor....

verify injector spray pattern is ok and not clogged or leaking....


just make make a list of possibilities and cover them one at a time otherwise we Will over complicate things in our heads.

Zaz1920

iTrader: (1)

I didn't have much time today, but I went and read the TPS values. Here's what I found:

Closed throttle:
VTA1: 0.64 V (supposed to be 0.10-0.70)
VTA2: 1.50 V (0.75-1.25)

Open throtte:
VTA1: 4.35 V (4.2-4.6)
VTA2: 4.97 V (4.8-5.0)

The high VTA2 values might be causing my issue. I'll have to adjust it when I get back from traveling for the holidays. If that's not it I'll do more vacuum leak hunting and if that's not it I'll go take a look at injectors again.

To answer your question, it is hunting. It'll go back and forth revving from around 700 RPM to 1000+ RPM.

Thanks for the help.

Zaz1920

iTrader: (1)

So I went and did some more checking today and am still coming up empty. First I let the car warm up before starting any work with the TPS. Once the car was warmed up the TPS values went back to normal. They were:

Closed:
VTA1: 0.45 V
VTA2: 1.05V

Open:
VTA1: 4.35 V
VTA2: 4.97 V

All are within values so I didn't do any adjustment.

Next I tried spraying some carb cleaner around to see if it affected the idle at all via a vacuum leak. No luck.

Next I suspected the injector o-rings might be an issue cuz I've had problems with them before. I turned the car off, ran the fuel pump for a minute or two to get pressure built up and see if there was any leakage into the engine. It started right up so I don't think that's the issue. If there were a problem with the injectors themselves, wouldn't it be running lean rather than rich??

I have attached a log of a little over 10 minutes of warmup going from a smooth startup to a rough idle once warmed up. I also took a few videos:

https://www.youtube.com/watch?v=oqA3...ature=youtu.be

https://www.youtube.com/watch?v=iz0g...ature=youtu.be

Any more ideas before I go tearing everything apart again?

There was also what seemed to be a coolant leak once the engine warmed up. There was some white smoke coming from around the turbo y-pipe and underneath the air pump. There was some coolant dripping down onto the vacuum hoses under there. It was pretty slimy. Only happened once the engine was completely warmed up and I shut it off immediately after seeing the smoke. Might have to go hunt that down before continuing hunting the idle problem.

Zaz1920

iTrader: (1)

I'm having trouble uploading the log file. I have both a .txt and an excel file with the info. Does anyone know a better way to upload it?

armans

iTrader: (2)

Running too rich results in idle fluctuation (needle bouncing up and down) like it is in your case. Check the fuel maps, make sure the tune is right, e.g. as a first step compare your current fuel maps with PFC's base maps, see how they differ etc.

Zaz1920

iTrader: (1)

Like I mentioned earlier I got it tuned at a shop and it ran great. My first guess was that the ECU somehow reset itself and that is why it is running poorly. I found that the map is still set up for 850cc primaries indicating that the tuned map I got at the shop is still installed. I've been trying to get a backup of this map from the shop so I can re-upload it to the ECU, but haven't heard back from them in a while.

However, I don't think that's the source of the problem because I hadn't touched the ECU between getting it back from the shop in proper working order and it starting to behave like this. That is why I am tracking down stuff like the TPS sensor, vacuum leaks, or problems with the injectors.

cstone94

iTrader: (3)

I'm having an issue really similar to this. My car developed a random 10.0 rich idle. Power FC has the correct injector sizes, but my INJ MAP has 1.000 across the whole map.

Zaz1920

iTrader: (1)

Do you have any idea how that happened? Were you messing with the settings at all?

Because my issue only really takes effect once the engine warms up, I'm thinking that something with sealing the injectors in didn't work quite right. It's definitely something mechanical instead of a software issue. I'll have to tear into it to figure it out.

cstone94

iTrader: (3)

Nope, going to get tuned this week hopefully it will get sorted out.